Analytic methods applied to a sequence of binomial coefficients |
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Authors: | Stephen M Tanny Michael Zuker |
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Institution: | Department of Mathematics, University of Toronto, Toronto, Canada M5S 1A1;National Research Council, Ottawa, Canada K1A 0R6 |
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Abstract: | In previous work we have shown that the binomial coefficients Cn··kr, r are strongly logarithmically concave for 0?r?n/(k+1)] and hence have at most a double maximum. Let rn, k be the least integer at which this maximum occurs. Properties of {rn, k}n, k are best derived by introducing the polynomial family Qk(x,y) defined by Qk(x,y) = ∏k+1j=1 1?(k+1)x+jy]?x∏kj=11?kx+jy]. It is shown that for each k there is a unique function ηk(y) defined on 0, 1/(k+1)] which is analytic in a neighbourhood of zero and which satisfies Qk(ηk(y), y)=0. Setting ηk(0)=δk, η1k(0)=αk we prove that rrn,k = nδk] onδk]+1 and further, that the number of times that rm,k = mδk]+1 for k+1? m ? n is asymptotically nαk. Several other properties of αk are derived, including 0<αk <1/2. |
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